Sunday

April 19, 2015

April 19, 2015

Total # Posts: 87

**chemistry**

The heat of solution of potassium acetate (KC2H3O2) in water is -15.3 kJ/mol. If 18.8 g of KC2H3O2(s) is dissolved in 655 mL of water that is initially at 25.8 °C, what will be the final temperature (in degrees Celcius) of the resulting aqueous solution? (Assume no heat ...
*March 3, 2015*

**Math (Pre-Calc)**

Find all the solutions of the equation in the interval {o,2pi) 5sqrt3 tan x+3=8sqrt3 tan x
*February 8, 2015*

**Physics**

A person weighs 150 N on the moon. If the acceleration due to gravity on the moon is 1.63 m/s2, what is the mass of the person?
*February 2, 2015*

**chemistry**

The ionic equation and net ionic equation and balance equation: A) Ca(OH)2 + HNO3 --> B) H2SO4 + Na2CO3 --->
*January 12, 2015*

**Math**

Condense the expression to the logarithm of a single quantity. 5lnx-6ln(x+2)
*November 14, 2014*

**math**

a picture framer has a board 10 1/12 feet long. the framer notices that 2 3/8 feet of the board is scratched and cannot be used. the rest if the board will be used to make small picture frames. each picture frame needs 1 2/3 feet of a board. at most, how many complete picture ...
*November 5, 2014*

**math**

trina works after school and on weekends. she always works three days each week. this week she worked 2 3/4 hours on monday, 3 3/5 hours on friday and 5 1/2 hours on saturday. next week she plans to work the same number of hours as this week, but will work for the same number ...
*November 5, 2014*

**Science (How Do I Do This?)**

A car skids to a stop at a traffic light, leaving behind a 8.25m skid mark as it comes to a rest. Assuming that the car is travelling at 14.5m/s and only the friction from the tires on the roadway stop the vehicle. Find the coefficient of friction
*November 4, 2014*

**math**

Explain why 2.15 and -2.15 are opposites.
*October 8, 2014*

**Math**

1.) Which of the following inequalities is true for all real values of x? a.) x^3≥^2 b.) 4x^2≥2x^2 c.) (3x)^2≥4x^2 d.) 2(x-3)^2≥2x^2-3 2.) Which following inequalities is true for all real values of x? a.) x^5≥x^4 b.) 5x^2≥2x^3 c.) (5x)^2&#...
*October 5, 2014*

**Algebra**

@ MathMate, Here is the original question; Write the equation of the line with slope -2 that passes through the point (-1, -3) in slope-intercept form. But I've tried to figure out how to do it and I'm literally stuck.
*September 15, 2014*

**Algebra**

Okay, so! I figured out how to get the Point-slope form to the question I was given which led me to y+3 =-2(x+1), but, now I'm stick on finding the Slope Intercept form to get my answer. Can someone help me? Thanks!
*September 15, 2014*

**Algebra 1**

How do you solve this? Thanks! y+3 = -2(x+1)
*September 14, 2014*

**Spanish 2**

Whoops! For #3, that was my other answer. My real answer is: Hicieron los deberes de ayer.
*May 19, 2014*

**Spanish 2**

@Sra, I did these three as well. 1.) You and I went to the movie. 2.) We used to go to the park. 3.) They did the homework yesterday. My answers: 1.)Usted y yo fuimos al cine. 2.)Solíamos ir al parque. 3.)Solía comprar libros para los estudiantes.
*May 19, 2014*

**Spanish 2**

Re-write the sentences in Spanish. Are my answers correct? Thanks! :) 1.) I used to eat. 2.) Clean!! 3.) You (informal) have seen the movie. 4.) I practiced yesterday. 5.) When I was young, I played soccer. My answers: 1.)Yo solía comer. 2.)Limpio! 3.)Usted ha visto la ...
*May 19, 2014*

**Algebra 2!**

1.) ƒ(x) = (x^4)/4 − 3x^3 + (23x^2)/2 - 15x. Find the x values where the extremes occur. 2.) On a 10 question exam each question is worth 10 points (no partial credit). How ways can you make a 70%? 3.) Write the polynomial in standard form. Then classify it by ...
*May 8, 2014*

**Algebra 2**

Hello! I need help with these four math problems. Thanks so much! :) 1.) ƒ(x) = (x^4)/4 − 3x^3 + (23x^2)/2 - 15x. Find the x values where the extremes occur. 2.) On a 10 question exam each question is worth 10 points (no partial credit). How ways can you make a 70...
*May 8, 2014*

**Math**

Seattle to wilderness=180mph wilderness to Seattle=225mph 225+180=405miles in 7 hrs 405/7=57.8571 mph 57.8571 miles
*March 17, 2014*

**Physics please help?????**

I got the complete equation 1/2*k*y^2 - m*g*y - m*g*3h0 and solved for y, and got 0.330 and its correct. Thanks.
*March 16, 2014*

**Physics please help?????**

A 540 g block is released from rest at height h0 above a vertical spring with spring constant k = 320 N/m and negligible mass. The block sticks to the spring and momentarily stops after compressing the spring 19.8 cm. How much work is done (a) by the block on the spring and (b...
*March 16, 2014*

**Physics**

A 540 g block is released from rest at height h0 above a vertical spring with spring constant k = 320 N/m and negligible mass. The block sticks to the spring and momentarily stops after compressing the spring 19.8 cm. How much work is done (a) by the block on the spring and (b...
*March 16, 2014*

**Math **

Write this equation as a logarithm of a power: w ln 4
*May 10, 2013*

**chemistry**

H2 + I2 -> 2Hl 1.2 mol of hydrogen gas reacts with 1.0 mol of iodine vapour, after 5 minutes 0.6 mol of iodine remained. A) calculate the number of moles of hydrogen that have not reacted after 5 minutes. B) calculate the number of moles of hydrogen iodide that have been ...
*December 12, 2012*

**science; AP Chem**

ooh ok, thank you very much! this site is seriously a life saver!
*September 15, 2012*

**6th grade math (please please answer!)**

because it is an equation, what you do to one side you must do to the other. In this case you are looking for what 'x' is, that is why it is labeled "x" because it is unknown. To find 'x' you must subtract 9 from the left side and then you must ...
*September 14, 2012*

**Physics**

Runner A is initially 2.4 km west of a flagpole and is running with a constant velocity of 8.4 km/h due east. Runner B is initially 2.2 km east of the flagpole and is running with a constant velocity of 7.4 km/h due west. What will be the distance of the two runners from the ...
*September 14, 2012*

**Physics**

Runner A is initially 2.4 km west of a flagpole and is running with a constant velocity of 8.4 km/h due east. Runner B is initially 2.2 km east of the flagpole and is running with a constant velocity of 7.4 km/h due west. What will be the distance of the two runners from the ...
*September 14, 2012*

**Chemistry**

in the reaction of aluminium and iron (III) oxide to form iron and aluminium oxide, H-850 kJ. how many grams of aluminium oxide are formed when 350 kJ are released? 2Al(s) + Fe2O3 -- Fe(s) + Al2O3(s) H=-850 kJ
*May 24, 2012*

**chemistry**

Determine the of mole of water molecules in one mole of a sample of an iron containing (nh4)2so4. FeSO4. nH2O. titrate a solution of the iron containg (solution Y)
*December 3, 2011*

**encryption**

Show that the active CCA against ElGamal encryption given in the lecture does not work when against the Cramer-Shoup encryption.
*October 18, 2011*

**MATH**

How do you go about finding equations to a given solution set?
*May 10, 2011*

**Physics**

1)How much work is done by a person lifting a 2 kg object from the bottom of a well at a constant speed of 2m/s for 5 s. Is the answer mgh=2*9.8*10m 2)A 2kg block slides on a rough horizontal surface. A force (magnitude = 4N) acting parallel to the surface is applied to the ...
*April 5, 2011*

**Chemistry**

I have a couple of questions I need a hand with: 1. Oxygen has a melting point of -218 degrees celcius and a boiling point of -183 degrees celcius. This means that oxygen would be a liquid at...? Please do not tell me the answer, but tell me the relation between the melting ...
*January 18, 2011*

**Chemistry**

Name one difference between acids and bases in terms of: -Their chemical formula -A property Any help would be awesome.
*January 14, 2011*

**trig**

a hedgehog wishes to cross a road without being run over. he observes the angle of elevation of a lamp post on the other side of the road to be 27 degrees from the edge of the road and 15 degrees from a point 10m back from the raod. How wide is the road??
*October 16, 2010*

**INTRODUCTORY ALGEBRA**

Hey, the result cant always be 3 as I did it with 6 and got 9, you would have to the square root that number to get 3. I dont agree with your answer as I cant see why you wld just multiply the degrees. Anyway thank you for your help and sorry I couldnt be more help with your ...
*October 16, 2010*

**college Finite**

Find the probability of at least 3 successes and at least 2 failures. N(trials)=10 and p=3/10
*October 10, 2010*

**college math213**

place parentheses, if needed, to make each of the following equations true: a.5+6.3=33 b.8+7-3=12 c.6+8-2/2=13 d.9+6/3=5
*July 27, 2010*

**Chemistry**

If 2 g of salicylic acid is heated with 4 g of acetic anhydride, what is the theoretical yield ? C7H6O3 + C4H6O3 --> C9H8O4 + C2H4O3
*April 17, 2010*

**math**

I need help to get started with writing the equation for the following problem: It takes a freight train 2 hours longer to travel 300 miles than it takes an express train to travel 280 miles. The rate of the express train is 20 miles per hour greater than the rate of the ...
*April 1, 2010*

**Math 6th**

Why do eskimos wash their clothes out tide? (can only be 10 letters)
*March 10, 2010*

**Physics-please help!!!**

A 190 g particle is released from rest at point A inside a smooth hemispherical bowl of radius 25.0 cm. Calculate the gravitational potential energy at A also, how do you find kinetic energy if you aren't given velocity? please help me! i would really appreciate it
*November 19, 2009*

**Math for educators**

Help please! What is the domain and range for the following numbers 2.68, 2.58, 2.38? Thank you
*November 8, 2009*

**math213**

2054
*November 7, 2009*

**English**

Thanks so much!
*September 12, 2009*

**English**

What if i have to quote 4 different lines in a dialogue between two people? They come to realize that money is the most important part of their everyday lives, as well as their pursuit of their dream. MAMA. Son-how come you talk so much ‘bout money? WALTER. (With immense ...
*September 12, 2009*

**English**

I'm not sure how to quote a dialogue from a play in my essay. And if it includes a line such as: WALTER(With immense passion) Because it is life, Mama! Do include the part in parethesis?
*September 12, 2009*

**I DONT KNOW**

WHAT IS THE DEFINITION OF ANTHROPOLOGY
*May 18, 2009*

**math**

THE ANSWER IS 5 OKAY?
*May 18, 2009*

**3rd grader needs help with grammar**

mY CLASSMATES AND i
*May 6, 2009*

**Language Arts/Poetry**

In the poem "Parade" by Rachel Field, what details in the poem describe the town? The only thing I see is the elm trees and the grass. Can you help me?
*December 17, 2008*

**history**

When was the Hellenic period in Greece?
*December 29, 2007*

**history**

Why did Alexander go to India? Was it for gold? Did he conquer any cities there or name any after himself? Thank you.
*December 28, 2007*

**history**

Where did Cleopatra die? Thanks much!
*December 23, 2007*

**Chemistry**

What is the suffix for an alcohol which contains more than three -OH groups?
*October 5, 2007*

**Chemistry**

Do you know the carbon chain lengths for the different states of alkynes? Eg alkanes having a carbon chain length of 1-4 are gases, 5-16 are liquids and 17+ are solids. Are there similar rules for alkynes?
*October 4, 2007*

**math**

how d you turn the roman numeral number DCCXXXI into a regular number?
*October 1, 2007*

**math**

how d you turn the roman numeral number DCCXXXI into a regular number?
*October 1, 2007*

**Chemistry**

Electrochemical Cells Out of platinum, iron, carbon and silver which would be the LEAST suitable as an electrode in a standard Fe3+/Fe2+ half cell, and why? Pt usually is the metal of choice for making measurements of this type, because of its inertness AND because of ...
*July 30, 2007*

**Chemistry**

Does sodium metal react with potassium hydroxide solution? No. It would be a displacement reaction and this only works if the metal is higher in the activity series than the one it wants to displace. Given that potassium is the highest ranked metal (sodium second), there ...
*July 28, 2007*

**Chemistry**

If a colourless liquid with a pungent odour is added slowly to another colourless liquid, a dark brown precipitate is produced that later dissolves to produce a colourless solution. What are the two colourless liquids?
*June 10, 2007*

**Chemistry**

Does the reaction between CO2(g) + Mg(OH)2(aq) produce MgCO3(s) + H2O(l) or Mg(HCO3)2 ??? Normally, Mg(CO3)2 but I suspect an excess of CO2 will produce the bicarbonate. For example, CO2(g) + Ca(OH)2(aq) ==> CaCO3(s) + H2O(l) and that is often done by exhaling into a flask ...
*May 31, 2007*

**Chemistry**

I'm trying to work out the equation for when ammonia solution is added to zinc hydroxide solution. I think a precipitate forms. [Zn(OH)4]2- + NH3(aq) + H2O(l) --> ???? Zn(OH)2 + 4NH3 ==> Zn(NH3)4(OH)2 The Zn(OH)2 forms a soluble complex ion with NH3.
*May 23, 2007*

**Chemistry**

What sort of chemical test can be performed to identify from two unlabelled powders which one is zinc hydroxide and which one is aluminium hydroxide? Look up the determination of metals with dithizone. I believe Zn gives a colored complex when extracted into CCl4 and Al will ...
*May 22, 2007*

**Chemistry**

If a solution of Ca(OH)2 has a pH of 12.31 how can I calculate the concentration of calcium hydroxide in mol L-1 ? Write the dissociation equation: Ca(OH)2 >>Ca+ + 2OH So the concentration of the OH ion is twice the Ca(OH)2 . Find the concentration of the OH ion [H+]= ...
*May 21, 2007*

**Chemistry**

If the hydrochloric acid is warm, is the following equation correct? 2HCl(aq) + Na2SO3 --> 2NaCl(aq) + SO2(g) + H2O(l) yes, correct.
*May 20, 2007*

**Chemistry**

How does one calculate the pH of a solution that is only 1.84% ionised? determine the concentration of the H+, which will be in a monoprotic acid, concentration * decimal percent. then determing pH in the normal way.
*May 20, 2007*

**Chemistry**

I have an assignment Q A 0.1 mol L-1 water solution of NH4CH3CO2 has a pH of approx 7. Explain this using two equations. I have one equation CH3COO-(aq) + H2O(l) --> CH3COOH(aq) + OH-(aq) What could the other equation be? NH4CH3CO2 is the salt of a weak acid and a weak base...
*May 18, 2007*

**chemistry**

Why is a solution of KNO3 neutral and not acidic? K^+ doesn't hydrolyze (H2O has a stronger attraction for the OH- than K^+) and NO3^- doesn't hydrolyze (H2O is a stronger base than NO3^- meaning that H2O will not donate a proton to NO3^-). Looking at it another way, ...
*May 13, 2007*

**Chemistry**

When we mix NaOH and H2SO4 we get the equation OH-(aq) + H+(aq) --> H2O(l) and if we mix H2CO3 and NaOH we get the equation 2OH-(aq) + H2CO3 --> 2H2O(l) + CO3-2(aq) Why aren't the two equations the same? ie only one mol of NaOH reacts in the first equation but two ...
*May 12, 2007*

**Chemistry**

When asked to name all of the ions and molecules present in a 0.1 mol L-1 solution of CH3COOH, why are there OH- ions present if the equation is CH3COOH(aq) + H2O(l) --> CH3COO-(aq) + H3O+(aq) ? The water ionizes in such a manner that the product of the concentrations of ...
*May 12, 2007*

**Chemistry**

I think I made a mistake with my previous question. I have two solutions potassium thiocyanate (KSCN) and iron (III) chloride (FeCl3). The reaction is Fe+++(aq) + SCN-(aq) <--> FeSCN++(aq) What will happen if the solution is heated? Will the reaction rate shift to the ...
*May 2, 2007*

**Chemistry**

1. What will happen if I add water to a FeSCN+2 solution? FeSCN+2(aq) + H2O(l) <--> ???? 2. Will the equilibrium shift to the left or right? The FeCNS++ is red colored. I think adding water will simply dilute the red color. Won't it react in any way? Small highly ...
*May 1, 2007*

**Chemistry**

If the oxygen being fed into the system 4NH3(g) + 5O2(g) <--> 4NO(g) + 6H20(g) + 950kJmol-1 is heated, how will the equilibrium shift? The reaction is exothermic, that is gives off heat, or raising the temperature. If heat is added, then the reaction will shift to undo ...
*May 1, 2007*

**Chemistry**

Which of the following reactions is exothermic? 1. Na(s) --> Na(g) 2. Na(g) --> Na+ + e- 3. Cl2(g) --> 2Cl(g) 4. Cl(g) + e- --> Cl-1 My guess is 4, but I'm not sure Here is what you do. For 1, do we think it will take energy to change Na as a solid to Na as a ...
*April 30, 2007*

**Chemistry**

for the reaction 4NH3(g) + 5O2(g) <--> 4NO(g) + 6H2O(g) if H = -950kJmol-1, does that mean it's an exothermic reaction? Ooops pressed Post too quickly. Yes it is exothermic. Delta H is negative so heat is lost from the system. If delta H is positive a reaction is ...
*April 30, 2007*

**science**

sorry to annoy anyone, but WHAT is the big idea of energy? i would really appreiciate a response In what context? Too much use. Not reneewable? Cost? availability? in the context of an ironsulphide reaction I still don't understand the question. explaining the iron/sulphur...
*April 25, 2007*

**Chemistry**

I have two substances potassium sulfate and potassium carbonate. They are unlabelled and I need to know which one is which. If I add HCl to each substance ie K2SO4(s) + 2HCl(aq)-->2KCl(aq) + H2SO4(aq) K2CO3(s) + 2HCl(aq)--> 2KCl(aq) + H2O(l) + CO2(g) What would I observe...
*April 24, 2007*

**algebra**

does log base of 4 sqrt(t/s)=1/2log base of 4 t - 1/2log base of 4s? sqrt=square root thanks yes yah thanks!
*April 21, 2007*

**Chemistry**

In the reaction 2H20(aq) --> O2(g) + 2H20(l) why doesn't increasing the pressure of oxygen have any effect on the reaction rate? Balance the equation first. What you have isn't balanced. Frankly, it doesn't look possible. You have two mols H2O on each side. Take...
*April 19, 2007*

**algebra**

I know that 10^-2.3=5.0 * 10^-3 How do I get 10^-2.6 in the same form as 5.0 * 10^-3? please and thank you! Punch in 10 on your calculator, then press the yx button followed by -2.6 and then press equal. You should get 2.51E-3 thanks, but mine just says: .0025118864
*April 18, 2007*

**Chemistry**

I have an assigment question that I need help with. The Q states that sodium hydroxide absorbs water from the atmosphere. Then the saturated NaOH absorbs carbon dioxide from the air to form a thin coating of sodium carbonate. A piece of sodium hydroxide has been left on a ...
*April 16, 2007*

**Chemistry**

If barium nitrate solution is added to sodium hydroxide solution does a precipitate form? Are there exceptions? I have an assignment Q that asks about the precipitate, and I thought that Ba(OH)2 was soluble. Barium hydroxide is moderately soluble, up to about .1M ...
*April 15, 2007*

**Chemistry**

Given four unlabeled compounds and four labels (potassium sulfate, potassium carbonate, chromium sulfate, and cobalt bromide) is there a simple test that will allow correct labelling of each compound? I take we are looking for a simple school lab type test? If only allowed one...
*April 13, 2007*

**chem**

For this problem, will someone please check my answer? How many grams of oxygen are produced in the decomposition of 5.00g of potassium chlorate? KClO3(s)--->KCl(s)+O2(g) [the equation may not be balanced] My answer is 1.96 g of O2. The balanced equation is 2KClO3 ==> ...
*March 22, 2007*

**Maths**

John leaves point A to travel 360klm and Joanne leaves point A 40 mins later and her cars speed is 18klm per hour faster than John's but they both arrive at the same time. What is their respective speeds? The both travel the same distance. distance=rate(time) distanceJohn...
*March 21, 2007*

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